Natural History- Dimondback terrapin

This gorgeous creature was found during a field tip to the South Carolina Aquarium- our guide picked him out of the water habitat set up for this turtles species as well as other aquatic species on display in the outdoor area. The scientific name for this guy is the Malaclemys terrapin and it gets its common name from the characteristic ridges found down the center line of its carapace. Additionally you can identify one of these from the leopard print like spotting on its skin. Its habitat is aquatic- typically brackish waters around the south eastern US. Its adaptations to its aquatic environment are clear with its webbed feet and they can also tell the difference between salinity levels in water to maintain their water balance- quite related to lecture!

The animal was about 7-8 inches long I would say and because of this size I would most likely guess it is a female as these specie are sexually dimorphic with females on the larger end and males on the smaller (usually around 5 inches). I would also say it is in its adult phase because of this size as well. I was in awe of this animal and its ability to gracefully guide through the water with many other Dimondback Terrapins. When placed back into the water this turtle swam over to a group of others of the same species and they were trying to crawl their way back up though a small waterfall in this display area. I thought it quite peculiar as I did not know these animals would congregate together like this. These animals are also quite unique as they have a very large geographical range for a turtle belonging to the Emydidae family. They can exist in salt water and fresh water environments, so I wonder what the salinity in this water is?

Natural History: Iguana iguana

During a hike in Costa Rica, a mature male Green Iguana (Iguana iguana) was spotted basking next to a waterfall during the early afternoon on a hot, sunny summer day. This particular iguana was much habituated to human visitors making him very easy to photograph.  The specimen was approximately 3-3 ½ feet long from snout to tail, indicating that he was mature and between 3-5 years old. To identify the sex of this individual, the sexual dimorphism of the lower jaw in males are large, swollen looking “jowls” below the ear giving the head a large, blocky shape. Another indicator is longer spikes along the back of male green iguana. Although difficult to depict from the image, this male showed turquoise coloration along his head and neck with iridescent red colorations between his eyes; common among many iguanas of this species. With regards to thermoregulation, this individual was perpendicular to the sun maximizing surface area receiving sunlight. However, the cool breeze next to a waterfall helped maintain an equilibrium favorable for his thermoregulation. It is no surprise that this basking area is his known to be his favorite. Guides explained that this iguana is common to the area and it was extremely common for him to be spotted there. It wasn’t until 15-20 minutes into swimming around the rocks that this 3 foot iguana was even spotted! It was exciting to see a reptile this large remain so calm around a large group of humans.

Article Review: Geographic variation in the pattern of temperature-dependent sex determination in the American snapping turtle (Chelydra serpentina)

Ewert Micheal, et al.

Sex ratios for the Chelydra serpentina are actually temperature dependent just like the sea turtles we studied in class. Interestingly the males are biased in moderate temperatures, while cooler temperatures have a female bias and hotter temperatures only produce females. In the article the males preferred a temperature of around 24.5 degrees Celsius. In the higher latitudes they have found that females made nests in very exposed locations which in turn would make the nest warmer. Another interesting fact they found was that at warmer locations embryogenesis was much faster so females would often pick higher latitudes to lay their eggs. Therefore the study found a tradeoff in the balancing of the male sex ratios with the speed of embryogenesis. This is especially troubling because when we consider how global warming could effect the sex ratios in these snapping turtle populations.

Source article: https://www.cambridge.org/core/journals/journal-of-zoology/article/geographic-variation-in-the-pattern-of-temperaturedependent-sex-determination-in-the-american-snapping-turtle-chelydra-serpentina/53B0514E374F3EA8E8488A90AB0A38B1#fndtn-information

Class Mascot Nomination

As some may guess, I love Diamondback Terrapin Turtles. I nominate this turtle for our class mascot. Diamondbacks are beautiful and fill a unique niche in the marsh system. Herpetology is a unique, awesome class, so it only makes sense to have this turtle represent it.

Article Review: Antimicrobial peptides in frog poisons constitute a molecular toxin delivery system against predators

Raaymakers Constantijn, et al.

Most poisonous herps have a highly specialized delivery system (fangs, spines or stingers) to ensure that small amounts of poison make it to the bloodstream of their prey (or predator). This study’s aim was to examine how frog poison enters the bloodstream, while most toxins lack the ability to penetrate epithelial tissue of the prey. Besides toxins, frogs also produce antimicrobial peptides (AMPs) as an immune response capable of killing a broad range of microorganisms through cell lysis. This study observed an alternate application of AMPs, confirming that these antimicrobial peptide secreted by frogs degrade and permeabilize the prey’s epithelial tissue allowing for efficient transmission of toxins to the bloodstream.

In addition to being effective in capturing prey, AMPs increase the effectiveness and efficiency of toxins as a predator defense. Not only do AMPs allow for the transmission of toxins into the bloodstream, but they also accelerate diffusion so quickly it serves effective in evading predators.

This study seemed interesting to me because amphibian AMPs have attracted researchers for years now due to their role as an immune defense mechanism and their potency against clinically important pathogens. It is a great example of how a well understood mechanism can also serve an alternative role as an anti-predator defense, as presented in this study.

Free access to the article is located using the link below:

https://www.nature.com/articles/s41467-017-01710-1.pdf

“Thermoregulatory behavior and orientation preference in bearded dragons"

My little brother just adopted a juvenile bearded dragon and I thought it would be interesting to learn more about them. I read the article “Thermoregulatory behavior and orientation preference in bearded dragons.” As learned in class, lizards will use various types of behavior to thermoregulate, including various types of orientation. This study looked at thermal orientation behavior of Pogona vitticeps (bearded dragons) in adults and neonatal. Previous experiments have suggested that learning may be a part in behavioral thermoregulation, though overall it is thought to be innate and learned response. They discussed body orientation as orientation preference and wanted to discover if it is bias and better understand the innateness. They hypothesized that “orientation would present as a thermoregulatory mechanism in bearded dragons.” It was predicted that “bearded dragons would display non-random orientation behavior in a thermal gradient, choosing to face towards a heat source rather than towards a cold source.” Lastly, they also hypothesized that “preference for orienting towards a heat source would be conserved across multiple life stages, which would support an innate hypothesis for orientation behavior.” (Black, 172)

All the bearded dragons they used were captive bread. Seventeen were adults and twenty-six were neonates. During the experiment, thermal and orientation preference were measured using video recording and temperature sensing. An image was shot every30 seconds for six to eight hours. Orientation was facing heat or facing away from heat and movement was moving or stationary.

After the trials, they described that adult bearded dragons oriented toward the heat when at cool temperatures and as selected temperatures were reached, orientation became random. Also, lizards that were stationary often faced towards the heat. When the neonatal were first placed into the trial containers, selected temperature was not subjective to orientation, though during the end of the experiment, “selected temperature was increased when neonates were facing the cold, compared to when facing toward the warmth.” (Black, 175)

It was concluded from their results that adults orientate as a behavior related to thermoregulation, which is what we discussed in class. Also, that the behavioral orientation is more innate than learned in the neonatal. One of the last main points was that “orientation as a thermoregulatory behavior in neonatal bearded dragons, while present, does not appear to be as precise or as impactful on selected temperature as it does in adults.” (Black, 176) The bigger they are, they more precise they have to be in regulating their temperature.

Written by: Ian R.G. Black, Glenn J. Tattersall.

https://ac.els-cdn.com/S0306456517302176/1-s2.0-S0306456517302176-main.pdf?_tid=36e6ae95-c33e-48bb-aff8-0df1e0098818&acdnat=1524499633_4966f4c2681b4853d4b0a53362b48197

The Eurasian invasion: phylogenomic data reveal multiple Southeast Asian origins for Indian Dragon Lizards

This article, published by Jesse Grismer et al., discusses the biological origins of Indian Dragon Lizards, scientifically named Draconinae Agamidae, and whether they come from Eurasian descent, or India, before the continents merged together. The study conducted a genomic DNA comparison of the Indian Dragon Lizards from muscle and liver tissues. Through DNA testing with other samples of older species, along with geographic and biographic data samples, it was concluded with a high degree of certainty that the fauna and flora of this time period (around 50 million years ago) was more likely to have occurred through land bridges, in which these reptiles crossed over into India from, proposed by the scientists as the Eocene Exchange Hypothesis. This scientific literature successfully proved those DNA extraction of Draconinae species the occurrence of a land bridge through Eurasia and India during this time, which can be used in future studies to account for how new species made their way across the world millions of years ago. The graph and diagram below shows the occurrence of these species and the way in which the scientists believe the countries moved over the course of the years and how this effected the evolution and relocation of these animals. 

• Jesse L. GrismerEmail author, 
• James A. SchulteII, 
• Alana Alexander, 
• Philipp Wagner, 
• Scott L. Travers, 
• Matt D. Buehler, 
• Luke J. Welton and 
• Rafe M. Brown

BMC Evolutionary Biology201616:43

https://doi.org/10.1186/s12862-016-0611-6

©  Grismer et al. 2016

Received: 17 December 2015

Accepted: 8 February 2016

Published: 19 February 2016

Natural History: Timber Rattlesnake

            On our last field trip to the Donnelley Wildlife Management Area, we observed a timber rattlesnake and its Latin name is Crotalus horridus. The snake seemed to be a juvenile and was about 20 inches long, which is much smaller than the typical adult timber rattlesnake size. It is typically pretty difficult to determine the sex of a snake without handling it because the cloaca is typically used to help determine the sex. The snake was acting pretty docile and one of our classmates actually almost stepped on it. Once it was seen, we all surrounded it and the snake still did not move. It was curled up and it seemed to be in a basking position. The snake was lying in a recently burned environment in what looked to be a long leaf pine ecosystem. The snake was only a couple of yards off the dirt road and would be pretty easily seen. After observing the snake, it was shocking to see how calm it was when surrounded by people. Also, it seemed kind of strange that the snake was in such an open area in the middle of the day. It was pretty easily seen and could definitely be seen by predators. As a whole, the snake seemed to be unfazed by the attention from all the people.